1. Field of Invention
The present invention relates generally to the field of content distribution. More particularly, the present invention is related in one exemplary aspect to the insertion of public, education and government (PEG) or other local programming in a digital content distribution network.
2. Description of Related Technology
Historically, delivery of content such as multimedia programs has been accomplished using analog transmission techniques such as over-the-air broadcast using the National Television Standards Committee (NTSC) transmission standard or analog cable transmission techniques, such as described in “Modern Cable Television Technology”, Walt Ciciora et al., Second Edition, Morgan Kaufman, 2004, incorporated herein by reference in its entirety. Over the last fifteen years, the traditional analog transmission techniques have been complemented or replaced by digital content distribution techniques such as the American Television Standards Committee (ATSC) digital television broadcasting standards, and the Opencable™ specifications of CableLabs, as well as a suite of specifications promulgated by the Society for Cable Television Engineers (SCTE). These well-known standards provide mechanisms for carriage of encoded video and audio content over a distribution network to customer premise equipment (CPE) such as a set top box (STB).
To further exploit the spectral efficiency and flexibility offered by digital content distribution techniques, so-called “all-digital” content distribution techniques have been proposed in recent years. These generally comprise an end-to-end digital transport and processing, ostensibly to increase transmission quality, network robustness, and network efficiency (e.g., spectral or bandwidth efficiency). In the context of cable television, however, such all-digital networks will also require digital set top boxes (DSTBs) or comparable digital-enabled devices in all subscriber installations (as opposed to some existing subscribers using ATSC tuners in e.g., their television set to receive and display analog signals from their coaxial cable directly). The general architecture of a hybrid fiber coaxial (HFC) content distribution network that delivers all-digital content to a consumer's home may take various forms and names, such as switched digital video (SDV), switched digital broadcast (SDB), all-digital, etc.
Digital distribution allows an economically efficient alternative to the traditional analog content distribution techniques. Digital content distribution also provides techniques for carriage of non-video, non-audio services such as closed captioning information, program guides, and other program-related information.
However, to date, not all services have made the transition to the digital delivery paradigm. Moreover, most existing deployments of “digital” content distribution over digital cable actually use a mix of analog and digital distribution techniques.
For example, the insertion of public, education and government (PEG) programming and other such “local” or edge-derived programming in a conventional analog cable delivery network is typically performed by inserting the analog programming at a headend or other location of an extant network multiplexer, and then transmitting the inserted content as part of the channel line-up (multiplexed transport stream) to users downstream from the hub or headend. Obviously, such a method suffers from the disadvantage that, inter alia, it cannot be implemented in a content delivery network in which an all-digital program multiplex is transmitted to customer premises.
Moreover, even if the (analog) local content could be delivered to the customer's DSTB (such as via a channel or transport outside the aforementioned program multiplex), an analog (e.g., NTSC) tuner would be required in order to receive and process the signals for display on the customer's display device. The additional of such analog tuners to all-digital set top boxes (or otherwise in their television, etc.) adds significant cost to these devices.
Alternatively, if the analog content were digitized before it were multiplexed at the headend or other existing multiplexer location, the analog signals (or digitized analog signals) would still need to be backhauled to the that location (e.g., headend), thereby requiring significant additional infrastructure and potentially inducing significant latency.
Various other methods for the distribution of local analog (e.g. PEG) content are known in the prior art. See for example, U.S. Pat. No. 6,198,744 to Huggins, et al. issued Mar. 6, 2001 entitled “ASYNCHRONOUS TRANSFER MODE (ATM) BASED VERY-HIGH-BIT-RATE DIGITAL (VDSL) SUBSCRIBER LINE COMMUNICATION SYSTEM AND METHOD” and U.S. Pat. No. 6,608,837 to Brodigan issued Aug. 19, 2003 entitled “DATA CAROUSEL FRANCHISE PROVISIONING”.
As illustrated by the foregoing examples, prior art techniques do not support insertion and formatting of a locally generated analog signal within a content-based network (e.g., HFC cable or satellite) so as to enable compatibility with soon-to-be pervasive DSTB installations. In order to support an all-digital offering with all-digital set top boxes, a new delivery model is required to digitize, distribute, receive and decode analog signals such as the aforementioned PEG content that originate not at the headend but in the outer reaches (e.g., “edge”) of a cable network. These external video sources are becoming increasingly common today in the distribution plant (especially at the edges thereof), and will need to be addressed in the all-digital cable network of the future. Existing solutions such as those described above do not address the cost efficient and flexible local insertion of such video (available locally in analog video format) in a digital format, and delivery thereof via the edge infrastructure of a content-based network.